CLN: added io.api for i/o importing functions

     moved excel functionaility out of io.parsers to io.excel
     added read_excel top-level function
       aliases from pandas.io.excel
     added read_stata top-level function, to_stata DataFrame method
       aliases from pandas.io.stata
       removed read_dta (replace by read_stata)
     added read_sql   top-level function, to_sql DataFrame method
       aliases from pandas.io.sql

DOC: doc updates for all the above and intro section to io.rst
BLD: switch MAJOR and MICRO
Merge pull request #3716 from cpcloud/version-fix

BLD: switch MAJOR and MICRO
TST: provide warning when using ExcelWriter/ExcelObject if from deprecated path

DOC: minor edits in 0.11.1

DOC: cookbook/io.rst doc updates

TST: py3 issue on catching test warnings in test_parser_deprecated
ENH: allow to_html and to_latex to take a file name as their first argument
Merge pull request #3693 from jreback/io_api

CLN: added io.api for i/o importing functions
Merge pull request #3702 from cpcloud/read-and-friends-path-or-buf

ENH: allow to_html and to_latex to take a path for their first argument
DOC: document read_html and to_html

remove import of read_html
DOC: fix reference to read_html
Merge pull request #3704 from cpcloud/read-write-html-docs

DOC: document read_html and to_html
API: deprecate unused DataFrame.replace arguments
DOC: clean up io docs and fix up links
Merge pull request #3720 from cpcloud/null-funcs-api-doc-generate

DOC: clean up io docs and fix up links
Merge pull request #3712 from cpcloud/deprecate-unused-replace-args

API: deprecate unused DataFrame.replace arguments